Manufacture of a flexible container

ABSTRACT

A method for the manufacture of a flexible container suitable for use as a water bed for livestock comprises providing a first layer of a flexible polymeric material, applying a mask insert to an inner zone of a first surface of the first layer, the mask insert being arranged spaced from edges of the first layer thereby to define a substantially continuous boundary zone, arranging a second layer of flexible polymeric material to lie adjacent the first layer with the mask insert sandwiched therebetween, and subjecting the assembly so formed to a treatment operation thereby to form a face to face seal between the boundary zone and the confronting surface region of the second layer.

This application is a 371 of PCT/IB97/00853, filed Jun. 26, 1997.

FIELD OF THE INVENTION

This invention relates to a method for the manufacture of a flexiblecontainer such as a flexible fluid container and in particular, thoughnot exclusively, to the manufacture of a flexible fluid containersuitable for use as a water bed.

BACKGROUND OF THE INVENTION

Many procedures are known for the manufacture of flexible fluidcontainers, such as the use of a moulding technique to mould plasticsmaterial. However, many of the known techniques are not suitable for themanufacture of heavy duty type fluid containers such as water beds,particularly water beds for cows and other heavy weight livestock.

The known techniques for manufacture of flexible fluid containers alsooften are suitable only for the manufacture of individual water beds. Inthe manufacture of, for example, livestock water beds, it may be desiredto provide an integral arrangement of a plurality of water beds.

OBJECTS OF THE INVENTION

The present invention seeks to provide an improved method of themanufacture of a flexible container which is suitable for themanufacture of a fluid container of a heavy duty type. It seeks also toprovide a method suitable for the manufacture of an integral arrangementof a plurality of a flexible containers.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a method for themanufacture of a flexible container comprising:

providing a first layer of flexible polymeric material;

applying mask means to an inner zone of a first surface of said layer,said mask means being arranged spaced from edges of the first layerthereby to define a substantially continuous boundary zone;

providing a second layer of flexible polymeric material;

arranging said second layer to lie adjacent said first layer with themask means sandwiched therebetween, and

subjecting the assembly so formed to a treatment operation thereby toform a face to face seal between said boundary zone and confrontingsurface region of the second layer.

The invention teaches that preferably each of the first and secondlayers is of vulcanisable polymeric material and that said treatmentoperation comprises the application of heat and pressure to vulcanisethe polymeric material, at least in the region of said confrontingboundary zone surfaces, and thereby form a vulcanised joint between thetwo layers.

One or both of the first and second layers may be reinforced.

The two layers may be layers of substantially wholly unvulcanisedpolymeric material which are each vulcanised and become united with oneanother at the boundary zone during a vulcanisation operation. One oreach of the layers may be of a kind having a reinforcement structurewhich is embedded in polymeric material. Preferably in each layer theembedded reinforcement lies sandwiched between two layers of polymericmaterial. A layer may comprise calendered material.

Suitable polymeric materials include:- NR, SBR, BR, NBR/PVC, BIIR, CIIR,IR, EPR, EPDM, CR, SIR, wherein said abbreviations have the followingmeanings:

NR Natural Rubber

SBR Styrene-Butadiene Rubber

BR Butadiene Rubber

NBR/PVC a blend of Acrylonitrile-butadiene rubber and Polyvinylchloride

BIIR Bromine-Isoprene-Isobutylene Rubber

CIIR Chlorine-Isoprene-Isobutylene Rubber

IR Isoprene Rubber

EPR Ethylene-Propylene Rubber

EPDM Ethylene-Propylene-Diene Monomer

CR Chloroprene Rubber

SIR Silicone Rubbers

Use may be made also of blends of materials, including blends of theforegoing. The materials are suitable also for an outer surface of theflexible container, i.e. to lie at least outwards of any embeddedreinforcement structure, and also for forming an inward facing surface.

The reinforcement structure may be a reinforcement fabric known per se.It may comprise a single layer of reinforcement fabric which providesreinforcement strength in two mutually perpendicular directions. Thereinforcement structure may comprise a plurality of reinforcement fabriclayers in which case one layer may provide reinforcement in a firstdirection and a second layer may provide reinforcement in a directionsubstantially perpendicular to said first direction.

Outwardly facing surfaces of the flexible fluid container may beprovided with a profiled surface, for example during a vulcanisationprocedure. Examples of methods for providing a profiled surface includethe use of a press plate and the use of an impression cloth.Vulcanisation may be performed in press means with a layer of impressionfabric lying between a press face and an outer face of at least one ofthe first and second layers whereby during vulcanisation said outwardlyfacing surface of a first or second layer has imparted thereto a surfacetexture representative of the impressed and subsequently removed fabriclayer.

The mask means may comprise a layer of a material which does not adhereto the confronting surface materials of either the first or secondlayers. Typically it is a substantially continuous, free of cut-outs,layer so as to prevent confronting surfaces of the first and secondlayers coming into contact inwards of the boundary zone.

Suitable materials for the mask means include water-tight rubber, BIIR,CIIR, IIR, polyester, nylon 6, nylon 6.6, rayon, aramide, polyvinylacetate, polyethylene, polypropylene, cellulose-acetate, silicons,teflon and metal foils.

The mask means may comprise two layers of a material which optionally,and preferably, adheres to a confronting surface of one of said first orsecond layers but which does not adhere to itself when subject to thetemperature and pressure of a vulcanisation operation. Suitablematerials include the aforementioned materials which inherently do notadhere to the material(s) of said first and second layers.

The mask means may be arranged to extend locally to an edge of the firstlayer to provide a localised region at which the boundary zone of thefirst layer does not become adhered to the second layer. This creates anembryonic access passage so that, in subsequent use of the container,fluid may be introduced into or removed from the fluid chamber createdbetween said first and second layers.

Alternatively, instead of providing that the mask means extends locallythrough the boundary zone, a tube may be positioned to extend throughthe boundary zone prior to the first and second layers being unitedtogether. That tube may be of a flexible type which may adopt a lay flatconfiguration during the forementioned treatment operation, or may be arigid tube such as a tube of e.g. a plastics, or a metallic materialsuch as stainless steel. If the mask means comprises a pair ofsuperimposed layers, an inner end of the tube preferably is arranged tolie between those layers.

The method may be applied to the manufacture of a flexible containerwhich is to contain a fluid which may be a liquid or gas. It may be acontainer which is to be filled with a high viscosity material, forexample of a paste like consistency. It may be filled with a mediumwhich is or becomes a foam; that foam may be a resilient foam.

The present invention provides also a method for the manufacture of aflexible container of a multi-chamber type comprising:

providing a first elongate layer of flexible polymeric material;

applying a plurality of mask means to said first layer to lie in alongitudinally extending series along the length the first elongatelayer with successive mask means spaced from one another and each spacedfrom longitudinal side edges of the first layer;

providing a second elongate layer of flexible polymeric material;arranging said second layer to lie adjacent said first layer with theplurality of mask means sandwiched therebetween, and

subjecting the assembly so for a treatment operation to form face toface fluid seals between the first and second elongate layers atboundary zones around each mask means.

Preferably the method comprises also providing means for independentfluid communication with each fluid chamber zone created in the regionof each mask means. The method may further comprises providing that eachcommunication means extends to a common longitudinally extended edge ofthe assembly.

The first and second elongate layers may be of vulcanisable material andmay be vulcanised in a step-wise manner in which a first part of thelength of the assembled layers is introduced into an elongate platenpress, subjected to heat and pressure and then moved either out from thepress or further along the length of the press so that another portionof unvulcanised material is introduced into the press. The assembledmaterial therefore moves in a step-wise manner through the press.Alternative vulcanisation procedures include the use of a Rotocure typepress or a long length flat continuous cure press. Subsequent tovulcanisation, the resulting multi chamber assembly may be rolled forstorage and transportation.

The method of the invention further provides that either prior orsubsequent to said treatment operation, valve means may be provided forcontrol of fluid into and out of the fluid chamber formed in the regionof each mask means. The method may comprise providing a sealing deviceto stop flow of fluid into and out of the fluid chamber region until thefluid chamber region is to occupied by a liquid; prior introduction ofunwanted air can thereby avoided.

The invention teaches that each boundary zone preferably is providedwith a width of at least 10 mm, typically at least 50 mm. The widthtypically will be less than 200 mm, for example in the order of 100 mm,but may be significantly more, e.g. in the order of 1000 mm, to providea zone for securing to a floor or other location point.

At least a part of the boundary zone may have a width in the range 70 to110 mm.

In the case of manufacture of an elongate assembly of a plurality offluid chamber regions, it is envisaged that some of the successivechamber sections will each be spaced by an intermediate boundary zone ofa width corresponding to that at an edge region and that someintermediate boundary zones will be of a greater width, for example inthe range 1.5 to 2 times of the edge boundary width at positions atwhich, for example, one series of containers is to be cut from anothercontainer or series of containers.

It is further provided that intermediate boundary zones of greater widthare provided at pre-selected positions spaced along the length of theassembly at positions corresponding to those at which the elongateassembly is to cut transversely to provide sections, i.e. groups ofwater bed mats of a required length, or to provide individual mats.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example,with reference to the accompanying diagrammatic drawings in which:

FIG. 1 is a perspective part of a water bed during a first stage ofmanufacture;

FIG. 2 is a perspective view of an assembled water bed incorporating thecomponent part of FIG. 1;

FIG. 3 is a plan view of part of an elongate assembly of water beds at afirst stage of manufacture, and

FIG. 4 is a schematic view of apparatus for use in the manufacture of anelongate assembly of water beds.

DETAILED DESCRIPTION OF THE INVENTION

For the manufacture of a single heavy duty water bed suitable for usefor cows and other such livestock there is provided a first flexiblelayer 10 of synthetic rubber having embedded therein a woven reinforcingfabric 11 of rayon.

A mask insert 13 of a material such as polyester, which does notinherently tend to bond to unvulcanised rubber during vulcanisation, isplaced on an upper surface 12 of the unvulcanised layer 10.

The mask insert 13 is pre-selected in shape so that when it ispositioned centrally of the surface 12 there is formed a border zone 14of a width in the order of 75 to 125 mm, the border zone extendingcontinuously around the mask insert 13 except near to one corner atwhich a flat rubber tube 15 is provided and arranged to extend with oneend adjacent an edge 16 of the layer 10 and another end 17 slightlyoverlying the mask 13.

A second layer 20 of reinforced rubber, of a construction correspondingto that of layer 10, is then laid over the boundary surface 14 and mask13. The resulting assembly is subjected to a vulcanisation processduring which the layers 10 and 20 are vulcanised to one another at theboundary zone 14.

Subsequently a valve device/collector 21 is fitted to the tube 15.

The resulting assembly is then injected with water through the tube 15into the fluid chamber zone 22 defined between the confronting, unbondedcentral zones of the layers 10 and 20 outside of the mask layer 13.

When the required quantity of water (or other liquid) is in the fluidchamber, the valve 21 is closed to seal the chamber 22.

For the manufacture of an elongate series of water beds suitable forlaying in a continuous strip to cover the floor areas of a plurality ofneighbouring cow cubicles an elongate strip 30 of unvulcanised,reinforced rubber, corresponding in construction to the aforedescribedlayer 10, has a series of mask inserts 31, placed thereon.

Each mask corresponds to the aforedescribed mask 13, and the masks lieat positions spaced apart in the direction of the length of the strip30.

Edge boundary zones 32, 33 at opposite side edges of the strip 30 are ofa similar transverse width, and some of the transversely extendingboundaries zones 34 are also of that width.

At intervals along the length of the series of mask inserts there aretransverse boundary zones 35 of a double width.

Alongside each mask insert 31 there is provided a lay flat tube 36 forsubsequent connection of a valve, the tube 36 corresponding to theaforedescribed tube 15.

To complete the assembly a second layer of unvulcanised materialcorresponding to the layer 30 is placed over the layer 30, the mask 31and tubes 36. The resulting assembly 37 is then advanced in step wisemanner through a platen press 38. At the exit region 39, subsequent tothe vulcanised material having cooled sufficiently, the lay flat tubes36 are each fitted with valve devices which are closed to preventunwanted entry of air into the fluid chamber zones defined by therespective mask inserts. If necessary a pump or other means is used towithdraw unwanted air from the fluid chamber zones prior to closure ofthe tubes.

What is claimed is:
 1. Method for the manufacture of a heavy-dutyflexible container comprising: providing a first layer of flexiblevulcanizable polymeric material; applying mask means to an inner zone ofa first surface of said first layer, said mask means comprising at leastone layer of continuous solid material and being arranged spaced fromedges of the first layer thereby to define a substantially continuousperipheral boundary zone; providing a second layer of flexiblevulcanizable polymeric material; arranging said second layer to lieadjacent said first layer so as to form an assembly comprised of bothlayers with the mask means sandwiched therebetween, said mask means a)preventing confronting surfaces of the first and second layers fromcoming into contact inwards of the boundary zone, and b) not adhering tothe confronting surface materials of either the first or second layers;and subjecting the assembly to a treatment operation comprising theapplication of heat and pressure thereby to vulcanize said vulcanizablematerial and to form a vulcanized joint between said boundary zone andconfronting surface region of the second layer, wherein said mask meanscomprise two layers of material which do not adhere to one another whensubject to the temperature and pressure of said vulcanization.
 2. Methodin accordance with claim 1, wherein each of said first and second layerscomprises a substantially wholly unvulcanized polymeric material. 3.Method in accordance with claim 1, wherein at least one of said firstand second layers is a reinforced vulcanizable polymeric material. 4.Method in accordance with claim 3, further comprising forming at leastone of said first and second layers from a material comprisingreinforcement sandwiched between two sublayers of vulcanizable polymericmaterial.
 5. Method in accordance with claim 4, wherein the twosublayers are of the same vulcanizable polymeric material.
 6. Method inaccordance with claim 1, wherein at least one of said first and secondlayers is a calendered material.
 7. Method in accordance with claim 1,further comprising forming at least one of said first and second layersfrom a reinforced material having a reinforcement which providesreinforcement strength in two mutually perpendicular directions. 8.Method in accordance with claim 1, wherein the mask means is arranged toextend locally to an edge of the first layer to provide a localizedregion at which the first layer does not become adhered to the secondlayer.
 9. Method in accordance with claim 1, further comprising tubemeans arranged to extend through the boundary zone prior to the firstand second layers being joined together.
 10. Method in accordance withclaim 9, wherein the tube means comprises a flexible and lay flat tube.11. Method in accordance with claim 9, wherein the mask means comprisesa pair of superimposed layers and an inner end of the tube means isarranged to lie between said superimposed layers.
 12. Method inaccordance with claim 1, further comprising providing valve means prioror subsequent to said treatment operation for control of fluid into andout of a fluid chamber formed between said first and second layers. 13.Method in accordance with claim 12, further comprising providing asealing device adapted to prevent unwanted air from entering said fluidchamber.
 14. Method in accordance with claim 1, wherein the boundaryzone has a width of at least 10 mm.
 15. Method in accordance with claim14, wherein the boundary zone has a width of at least 50 mm.
 16. Methodin accordance with claim 14, wherein at least a part of the boundaryzone has a width of less than 200 mm.
 17. Method in accordance withclaim 1, wherein an outwardly facing surface of the flexible containeris provided with a profiled surface.
 18. Method in accordance with claim17, wherein said profiled surface is formed during a vulcanizationprocedure.